The invention concerns a screwdriver for an inner profile screw with a shaft and an outer profile head designed to correspond to the inner profile recess of the inner profile screw, in particular for use in connection with the surgical implantation of an implant into the body of a human being.
For example, during the implantation of a splint to be screwed to a bone, profile screws are normally used in conjunction with a screwdriver whose head is provided with an outer profile head which engages with the screw inner profile recess. Before screwing, it is important that the inner profile screw is held in such a way to the head of the screwdriver that it can not slip out.
From DE 1 866 996 such a screwdriver is known, which works in conjunction with a hollow head screw, and whose shaft is split into two half-sections by a longitudinal gap, which splay themselves apart due to their spring action, and so jam themselves into the screw head. From U.S. Pat. No. 4,779,494 a similarly developed screwdriver is known, with which the non-forcedly separated sections of the shaft are aligned by pushing a bushing forward.
In the case of prior art screwdrivers, they produce a clamping force, with which the section of the shaft is pressed against the inner profile recess in the inner profile screw, from the elasticity of the material of the shaft pushed back into the splayed position. The clamping force is therefore not precisely defined, but is dependent on tolerances (also in respect of the inner profile recess of the screw).